Question

George works as an office clerk and his office job pays him $12 per hour. Dorothy works as a cashier and her job pays her $11.25 per hour. Together, they worked 48 hours and earned a total of $555. How many hours did Dorothy work in her job?

Answer 1

You will need 2 equations, since there are 2 variables (hours worked by George and the ones of Dorothy), let's say x and y respectively

We know
x+y=48 (since they work 48 hours together) and
12x+11.25y=555 (since the sum of their respective hours multiplied by their salary gives a total of 555$)

To solve that, you can isolate either one of the variables and replace it in the second formula, for example:

x+y=48, therefore x=(48-y)
Substitute x in 12x+11.25y=555 and solve for y (to find Dorothy's hours)
12(48-y)+11.25y=555
576-12y+11.25y=555
21=0.75y
y=28